Slightly heavy particle system for wastewater treatment

Abstract

A slightly heavy particle system for wastewater treatment includes a contactor. The contactor includes a gas-liquid-solid three-phase region, and the gas-liquid-solid three-phase region includes gas phase, liquid phase, and solid phase. The liquid phase is the continuous phase and the solid phase is slightly heavy particles. The slightly heavy particles are able to carry some microorganisms on their surfaces at least, and the density of the slightly heavy particles is higher than the density of the liquid. The slightly heavy particle system applied in wastewater treatment can increase the concentration of microorganisms significantly, improve the ability to bear impact load, produce less sludge, and without sludge expansion. Meanwhile, suspending slightly heavy particles with the combined effect of gas and liquid is able to reduce energy consumption to a larger extent. Therefore, this system features with high efficiency and low energy consumption.

Therefore, what is claimed is: 
     
         1 . A slightly heavy particle fluidized bed system for wastewater treatment, comprising:
 a contactor enclosing a chamber, a liquid wastewater inlet near a bottom of the chamber for flowing liquid wastewater into said chamber, said chamber enclosing a gas-liquid-solid three phase region within said chamber when gas is being injected into said chamber when liquid wastewater is flowing into said chamber and when a solid phase is located in the liquid wastewater, said liquid wastewater being a continuous phase and said solid phase comprised of slightly heavy particles, said slightly heavy particles having microorganisms on their surfaces; and   a gas injection system which includes a gas source and a plurality of aeration tubes connected to said gas source for injecting gas into said chamber located at a bottom of said chamber and below the liquid wastewater inlet to give a uniform array of aeration tubes extending across the chamber to inject gas upwardly into said liquid wastewater phase containing said slightly heavy particles located in said chamber, the gas being injected at a gas flow rate that allows the slightly heavy particles to be generally uniformly dispersed in the chamber by the injecting gas, and wherein said plurality of aeration tubes are configured so that the gas phase flows upwardly in said chamber continuously or intermittently to form a fluidized bed with the slightly heavy particles uniformly dispersed therein; and   wherein the gas injected upwardly into the liquid phase containing the slightly heavy particles causes the slightly heavy particles to be uniformly dispersed and suspended in the liquid phase and not undergoing directional flow circulation.   
     
     
         2 . The slightly heavy particle system for wastewater treatment according to  claim 1 , wherein the density of said slightly heavy particles is higher than the density of said liquid wastewater and lower than or equal to about 150% of the density of said liquid wastewater. 
     
     
         3 . The slightly heavy particle system for wastewater treatment according to  claim 2 , wherein the density of said slightly heavy particles is lower than or equal to about 120% of the density of said liquid wastewater. 
     
     
         4 . The system for wastewater treatment according to  claim 1 , wherein when there is no gas injection said liquid wastewater and said slightly heavy particles form a liquid-solid two-phase region. 
     
     
         5 . The slightly heavy particle system for wastewater treatment according to  claim 1 , wherein an environment of said contactor is anaerobic, anoxic, or aerobic. 
     
     
         6 . The slightly heavy particle system for wastewater treatment according to  claim 1 , wherein said injection system is configured to be operated in two modes, a first mode being to flow the gas continuously upwardly, and a second mode being to flow the gas intermittently upwardly so that said slightly heavy particles are dispersed in said liquid wastewater. 
     
     
         7 . The slightly heavy particle system for wastewater treatment according to  claim 1 , wherein when liquid wastewater, slightly heavy particles and gas is present a gas-liquid-solid three-phase region is formed and wherein, the volume fraction of said gas phase is less than or equal to 25% in said gas-liquid-solid three-phase region. 
     
     
         8 . The slightly heavy particle system for wastewater treatment according to  claim 1 , wherein the shape of said contactor is a regular shell or an irregular shell. 
     
     
         9 . The slightly heavy particle system for wastewater treatment according to  claim 8  wherein said regular shell is a rectangular shell, and wherein the lower surface of said rectangular shell is fully closed or partially closed. 
     
     
         10 . The slightly heavy particle system for wastewater treatment according to  claim 1 , wherein the density of said slightly heavy particles is uniform or non-uniform and wherein the size of said slightly heavy particles is uniform or non-uniform. 
     
     
         11 . A process for wastewater treatment using a slightly heavy fluidized bed particle system including steps of:
 feeding wastewater into said slightly heavy particle system comprising: a contactor enclosing a chamber, said chamber including a liquid wastewater inlet near a bottom of the chamber for flowing liquid wastewater into said chamber, a solid phase comprised of slightly heavy particles, said slightly heavy particles having microorganisms on their surfaces, said slightly heavy particles having a density that is higher than the density of said liquid wastewater phase; and   injecting gas into said chamber located along a bottom of said chamber using a gas injection system which includes a gas source and a plurality of aeration tubes connected to said gas source spread uniformly across the chamber to inject gas upwardly into said liquid wastewater phase containing said slightly heavy particles located in said chamber, the gas being injected at a gas flow rate that allows the slightly heavy particles to be generally uniformly dispersed in the chamber by the injecting gas, and wherein said plurality of aeration tubes are configured so that the gas phase flows upwardly in said chamber continuously or intermittently to form a fluidized bed with the slightly heavy particles, wherein the gas injected upwardly into the liquid phase containing the slightly heavy particles causes the slightly heavy particles to be uniformly dispersed and suspended in the liquid phase and not undergoing directional flow circulation; and   discharging the treated wastewater from said slightly heavy particle system.   
     
     
         12 . The process according to  claim 11 , wherein multiple slightly heavy particle systems are coupled serially together and are interconnected by pipes, and wherein each chamber of each slightly heavy particle system has contained therein fluidized slightly heavy particles, and wherein no chamber is absent fluidized slightly heavy particles. 
     
     
         13 . The process according to  claim 11 , wherein said slightly heavy particles are added and discharged continuously or intermittently in said slightly heavy particle system. 
     
     
         14 . The process according to  claim 11 , wherein said liquid wastewater is flowed into and discharged from the chamber continuously or intermittently in said slightly heavy particle system. 
     
     
         15 . The process according to  claim 11 , wherein said liquid wastewater is flowed into the chamber from the bottom of said gas-liquid-solid three-phase region. 
     
     
         16 . The process according to  claim 11 , wherein said gas is aerated intermittently when the environment of the contactor is anaerobic or anoxic and said gas is aerated intermittently or continuously when the environment of the contactor is aerobic. 
     
     
         17 . A waste water treatment system, comprising a plurality of slightly heavy particle fluidized bed systems, each slightly heavy particle fluidized bed system of the plurality of slightly heavy particle fluidized bed systems being according to  claim 1 , wherein the slightly heavy particle fluidized bed systems of the plurality of slightly heavy particle fluidized bed systems are coupled serially together and are interconnected by pipes, and wherein each chamber of each slightly heavy particle fluidized bed system has contained therein fluidized slightly heavy particles, and wherein no chamber is absent fluidized slightly heavy particles.